429.08 NGC1448 and IC 3639: Two Concealed Black Holes Lurking in our Cosmic Backyard Unveiled by NuSTAR (Daniel Stern)

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Jan 7th at 1:00 PM until 2:00 PM




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Author(s): Daniel Stern11, Peter Boorman18, Ady Annuar5, Poshak Gandhi18, D. M Alexander5, George B Lansbury5, Daniel Asmus6, David R. Ballantyne8, Franz E. Bauer16, Steven E. Boggs17, W. Niel Brandt13, Murray Brightman2, Finn Christensen4, William W. Craig17, Duncan Farrah19, Andy D. Goulding14, Charles James Hailey3, Fiona Harrison2, Sebastian Hoenig18, Michael Koss7, Stephanie M. LaMassa12, Alberto Masini9, Stephen S. Murray10, Claudio Ricci15, Guido Risaliti1, David J. Rosario5, Flora Stanley5, William Zhang12

Institution(s): 1. Arcetri, 2. Caltech, 3. Columbia, 4. DTU-Space, 5. Durham University, 6. ESO, 7. ETH-Zurich, 8. Georgia Tech, 9. INAF, 10. Johns Hopkins, 11. JPL/ Caltech, 12. NASA GSFC, 13. Penn State, 14. Princeton, 15. PUC, 16. Space Science Institute, 17. Space Sciences Laboratory, 18. University of Southampton, 19. Virginia Tech

We present NuSTAR observations of two nearby Active Galactic Nuclei (AGN), NGC 1448 and IC 3639, located at distances of 12 Mpc and 54 Mpc, respectively. NuSTAR high-energy X-ray (> 10 keV) observations, combined with archival lower energy X-ray observations from Chandra and Suzaku, reveal both sources to contain heavily obscured, accreting super-massive black holes. NGC 1448 is one of the nearest luminous galaxies to the Milky Way, yet the AGN at its centre was only discovered in 2009. Using state-of-the-art models, we constrain the obscuring column density (NH) of gas concealing both AGN, finding them to be extreme, with NH values well into the Compton-thick (CT) regime with N(H) > 3e24 /cm2. NGC 1448 has an intrinsic X-ray luminosity of L(24 keV) _ 5e40 erg/s, making it one of the lowest luminosity CT AGN known. IC 3639, on the other hand, has one of the strongest iron fluorescence emission lines known. We also discuss multi-wavelength diagnostics at optical and mid-infrared energies as indirect indicators to penetrate through the obscuring veils and probe the intrinsic properties of the AGN. Through detailed studies such as we present here, NuSTAR is showing that there are still plenty of interesting discoveries awaiting to be made, even in the nearby Universe.

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